It worked the exact same as spar rating from PC Graal... The GS leaderboard still uses it.

There was a glitch that allowed players to constantly reset their deviation to /350 and cheat to #1. It was abused a ton. Aside from that, it basically encourages you to selectively spar when you're ranked high. When I was 9000+, I'd get +2 points for beating anyone and -100 for losing to #2.

You could also get ranked high on alternate accounts. It took about 30 spars to get ranked. It took over a week to hide from the leaderboard due to inactivity. After a week, all you had to do was spar a single time and you'd show again... A good player could sit at #1 by sparring probably 100-200 times the entire season. A bad player could do the same if they know the glitches and were selective enough.

I was #1 on the PC side of that leaderboard for probably 90% of the time I actively sparred through 2012-2014. It was clearly more reflective of skill, that's never been the argument, but it came with a ton of other problems.